This invention relates to an electronic sensing and display system for use in a temperature controlled device, such as a refrigerator. The sensing and display system monitors various sensed conditions and indicates the status of the sensed conditions to the user through the use of visual and audible indicating means.
It has been found desirable to inform a user of the status of various operating conditions in a refrigerator. By providing an indication of the status of these sensed conditions, the user is alerted to the existence of an abnormal condition which may result in a loss of food quality, or even food spoilage.
Furthermore, the existence of an abnormal condition within the refrigerator may indicate that an equipment malfunction has occurred. In such a case, it is desirable to alert the user as to the existence of such a malfunction so that corrective maintenance can be effected without undue delay.
It has also been found expedient to not only indicate the present existence of an abnormal condition, but to indicate whether the abnormal condition has existed for greater than a particular length of time. Moreover, it is desirable to provide a positive indication of whether an abnormal condition has previously occurred, but has since disappeared. An example of such an abnormal condition is an overtemperature occurrence within the refrigerated airspace of longer than a predetermined length of time. In such a case, food spoilage may have resulted, even though the temperature within the refrigerator has since returned to normal levels. Such a condition, if not indicated, may result in the consumption of spoiled food, which obviously should be avoided.
In some prior refrigerator sensing and indicating systems, a visual indication is provided when an overtemperature condition is sensed. Some of these types of systems provide an additional indication whenever the overtemperature condition has existed for longer than a predetermined period. Other systems of this type require acknowledgement, i.e. manual intervention, by the user before the system can be returned to its normal state. However, these types of systems do not provide a separate indication that a previous overtemperature condition has occurred, but that the condition has since disappeared so that the refrigerator has returned to normal operating temperature levels. Consequently, such systems do not indicate whether or not the overtemperature condition is still in existence.
Other types of sensing and indicating systems have utilized scanning apparatus to sequentially scan and indicate the status of various sensors. In one such system, the scanning operation is stopped automatically when an alarm condition is detected, so as to indicate which sensor is registering an abnormal condition. However, such types of systems suffer from the disadvantage of scanning the sensors and the indicators at the same time and rate, which may result in an abnormal condition being undetected while another abnormal condition is being indicated.
A still further type of monitoring and display system concurrently scans a first number of sensors while continuously sensing a second number of sensors. The status of each of the first group of sensors is sequentially displayed at the same time and at the same rate as the scanning rate. If one of the continuously sensed conditions assumes an abnormal value, the scanning is interrupted and the status of the continuously sensed condition is immediately displayed.
In still another type of sensing and display system, a number of test points are scanned and a visual indication of the status of each test point is concurrently actuated. In addition to these indicators, the display panel includes a run light which flashes each time data is sent to the display unit. The sequential energization rate of the visual indicators, however, is synchronized to the actual sensor scanning rate itself.
These and other types of sensing and display systems do not disclose the use of a display having a series of sequentially energized scanning indicators which provide a general indication that sensor scanning is taking place, together with a plurality of separate warning indicators that are energized only when an abnormal condition is sensed, and in which the sensor scanning operation continues even when the existence of an abnormal condition has been indicated.